King's announcement Tuesday came a couple of weeks after he celebrated his 25th anniversary with a week of shows interviewing President Barack Obama, LeBron James, Bill Gates and Lady Gaga — precisely the unique blend of stars and statesmen he considered the signature of "Larry King Live."

King said he will continue to do occasional specials for CNN after stepping down in the fall. He was already lobbying for guests for his final week on Tuesday, extracting a promise to appear from ABC's Diane Sawyer when she called in to his show to congratulate him.

The longtime radio host was a pioneer in cable television. From the first show, on which he interviewed then-New York Gov. Mario Cuomo, King's desk was considered a valued spot for anyone interested in talking to the nation. King's interview style was plainspoken, and critics would suggest occasionally ill-prepared, but he was good at making his guests feel comfortable.

Klein said King was a pioneer.

"He lured so many people to this new frontier of cable back before anybody understood what it was all about," said Klein, who called King a "living, breathing Hall of Famer who is still doing the work."

As cable news audiences gravitated toward politically pointed shows and newsmakers found many more outlets for interviews in recent years, King slipped in the ratings behind Fox News Channel and MSNBC — two networks that didn't exist when he first turned on his TV microphone. During his interview with Lady Gaga, the 76-year-old broadcast veteran had people wondering if he was really connecting with a pop star a half-century his junior.

King said he felt no pressure from CNN to leave. He said he began thinking about stepping down as a plane flew him home to Los Angeles from Akron, Ohio, where he interviewed James, and he reflected on his big-name guests of the week.

"I said, 'I can't top this,'" King recalled in an interview Tuesday.

"I'm tired of the nightly grind," he said. "I do want to do other things, but I want to stay at CNN in some way ... . There's a case of great mixed emotions."

King told his staff Tuesday during a conference call he referred to as "one of the saddest 10 minutes of my life."

CNN is in the midst of remaking its prime-time lineup and last week announced that former New York Gov. Eliot Spitzer and conservative columnist Kathleen Parker would co-host an 8 p.m. EDT show on politics and current events.

CBS News anchor Katie Couric has long been considered a potential successor to King. That talk has cooled lately with suggestions that Couric may be reluctant to take responsibility for another network with ratings troubles; Klein would not discuss specific candidates. Recent published reports have suggested that "America's Got Talent" judge Piers Morgan could be a candidate. King said if it were up to him, "American Idol" host Ryan Seacrest would be the best choice to fill his shoes.

King estimated he's conducted 50,000 interviews during a 53-year broadcasting career. He said he always tried to ask short questions and to never come in with an agenda, leaving his ego at the door.

"I never learned a thing while I was talking," he said. "That would be my motto."

King got some sympathy from comic Bill Maher, invited as a guest on "Larry King Live" on Tuesday specifically to be there on the night of the announcement.

King dismissed a series of stories this spring questioning his future and speculating about possible successors.

"You can't worry about things you can't control," he said. "I can't control if a newspaper is going to speculate about something or if a blog is going to speculate ... . If I let it get me, I'll go nuts. So what I try to do, and I'm not being morbid, I just try to do the best show I can. If it works, it works."

King said he was able to see the baseball all-star games of his sons this weekend. If it was during the week, he'd miss them.

"I'm never going to see these again," he said. "They're not going to repeat themselves. They're 11 and 10. They're not going to be 11 and 10 again."

Besides work with CNN, King said he'd be interested in working in comedy.

Maher said on the show that, speaking for a lot of people in America, "I will miss you terribly at this hour."